The majority of showcase cabs I have seen came with a Sharp Image monitor, either a SI series or KT series (rebranded Kortek). The resolution depended on the game.
I seem to recall that Point Blank 2 had switchable resolution, but I could be wrong.
So really there could be any monitor in that cab, might even be a switchable res monitor. The only way you are going to know for sure is to look at it, get a model number or pic of the chassis.
As for the price, $250 seems like a very good deal. Regardless of the monitor type, if the tube is still bright and sharp the monitor itself is probably worth that. 33" monitors ain't cheap!
D